Our long range objective is to determine how the soluble and membrane protein components of various types of secretory vesicles are synthesized and assembled into the functional organelles. We will study the incorporation of 3H-luceine into specific membrane bound and soluble protein of chromaffin vesicles employing a newly developed system for maintaining cultures of isolated adrenal medulla cells. Using techniques of subcellular fractionation and immunoprecipitation we will determine the time sequence for the synthesis of the specific proteins of certain variables such as stimulation cyclic AMP and cyclic GMP on vesicle formation. In studies on rat parotid gland we will investigate factors which may be involved in the intracellular transport of protein from their sites of synthesis in the endoplasmic reticulum to the mature zymogen granule.